Why do baboons make a loud sound?

Male baboons eavesdrop on mating couples to determine the status of their relationships, scientists show. Mating chacma baboons produce an incredible amount of noise; males grunt and females emit loud and long operatic calls. This is because higher-ranked, more dominant males otherwise monopolize high-ranked females.

Explanation:

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.